Rust-proofing iron and steel surfaces.



time :i sir WALTER I. OESCHGER, OF DETROIT, MICHIGAN, ASSIGNOR TO PARKERRUST PROOF COMPANY OF AMERICA, OF DETROIT, MICHIGAN, A CORPORATION OFMICHIGAN.

RUST-PROOFING IRON AND STEEL SURFACES.

No Drawing.

To all whom it may concern:

Be it known that I, WALTER I. Onsoncnn, a citizen of the United States,and residing at Detroit, in the county of Wayne and State of Michigan,have invented a new and Improved Process of Rust-Proofing Iron and SteelSurfaces, of which the following is a specification.

This invention relates to a process of forming non-corrodible protectivesurfaces on articles made from iron or steel, or alloys thereof, and tothe production of the materials to be used in such process, and has forits object certain improvements in the method of treating said articlesand in the compounds or materials used to produce permanent surfaces,which, while not injuriously affecting the ferrous masses, will retaintheir efficiency as a protective medium against the action of theelements of the atmosphere.

The articles of iron and steel to be treated are placed in a bath whichis usually kept at about the boiling point, but the exact temperatureand the proportioning of the constituent elements of the bath aredetermined by the metallurgical character of the articles to be treated.The preferred composition of the bath is about 98 per cent. of water andless than two per cent. of a metallic phosphate such as the acidmeta-phosphates of tungsten, molybdenum or of any of the metals of thethird, fourth and fifth groups, according to the analyticalclassification (set forth by Prof. G. S. Newth, F. I. C., F. C. S., inthe eighth edition of his Manual of (J'hemz'cal Analysis, published byLongmans, Green & Co., New York, in 1909), taken either singly or incombination with each other.

In this classification, tungsten is in the first group, molybdenum inthe second group, while the third, fourth and fifth groups includealuminu rn, chromium, cobalt, iron, nickel, manganese, zinc, barium,strontium, calcium, sodium, potassium, magnesium and vanadium.

The acid meta-phosphate of most general application is made by placing aquantity of iron oXid, preferably black iron scale, (Fe,O,) in a potwith sufficient phosphoric acid to form a soft paste. The iron oxid ispreferably powdered in advance. An

Specification of Letters Patent.

amount of water equal to the acid is added to keep the mass from caking,after which heat 'is applied and the material is stirred until a drygranular mass is obtained,which isthen powdered. If desired, heat may beapplied to the oxid and acid before water is added. To obtain thephosphates of the other metals, their oxide or carbonates may besimilarly treated. Care must be taken to avoid heating these phosphatesto a point where there is more than merely perceptible fuming.

The reactions may be expressed as follows :When heated And continuedheating results in driving off the water of combination This is an acidmeta-phosphate.

The acid meta-phosphates thus produced are placed in water in theapproximate proportions above set forth. It has been found that apercentage of phosphates as low as one-half of one per cent. will servethe purpose intended, butthat the action Will be slow. If more thantwoper cent. of phosphates are placed in the bath, the action is quiterapid and at times rather uneven. The preferred proportion of the acidmeta-phosphates is about one and one-half per cent. The best action issecured when the bath is kept at about the boiling point.

It has been found that the mixing of about two per cent. of strontiumacid meta-phosphate with the iron compound above described gives a muchmore uniform and harder surface when high carbon steels are treated.Practically the same good result is attained by using the samepercentage of molybdenum or tungsten acid meta-phosphates instead of thestrontium acid metaphosphate in combination with the iron compound.There is little advantage in using any of these acid meta-phosphatesalone or in any combination that does not include iron acidmeta-phosphate as the cost is much higher and the addition of a largepercentage of iron acid meta-phosphate seems to have no objectionableeffect. Articles treated in this manner do not have Patented Jan. 22,191.

. Application filed February 21, 1917. Serial No. 150,015.

the pickled appearance sometimes observed when ferric-acid-phosphatesare used for this purpose.

I claim: v r

1. A new and useful process consistin of heating iron oxid with waterand p osphoric acid and stirring while continuing the heat until agranular mass is obtained, placing this in an excess of Water, heatingthe bath and immersing articles of iron or steel until. a protectivecoating is formed thereon.

2. A new and useful process consisting of.

placing acid meta-phos hates of tungsten, molybdenum or any 0 the metalsof the third,-fourth and fifth groups in an excess of water, andimmersing therein articles of iron or steel.

3. A new and useful process consisting of placing the acidmeta-phosphates of tungsten, molybdenum or any of the metals of thethird, fourth and fifth groups in an excess of water, and immersintherein articles of iron and steel while the ath is kept atsubstantially the boilin point.

4. A new and use ul process consisting in mixing iron oxid andphosphoric acid and heating them, adding water and stirring while theheat is continued, grinding the dry mass topowder, adding the powder tofifty times its Weight of water and two per cent. of'its Weight inmeta-phosphate of another metal, then immersing articles of iron orsteel to be treated.

:WALTER 1. OESCI-IGER.

